Method and apparatus for vulcanizing inner tubes or the like



May 4 1926.

. 1,583,520 J. C. BOLT METHOD AND APPARATUS FOR YULCANIZING INNER TUBES on THE LIKE Filed Jan. 5, 1925 IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII INVENTOR. v J0$PH C. BOLT BY O P 1 ATTORN;% I

Paten ted 'May 4,1926. I a i 7 1,5335% UNIT-ED STATES. PATENT OFFlCE.

JOSEPH CLARENCE BOLT, OF IBOUNDBROOK, NEW JERSEY. METHOD AND APPARATUS 1:01tVUL'Z'JANTZING INNER TUBES OR THE LIKE.

Application filed January 5, 1925. Serial No. 494.

To all whom it may concern; tube and thereby prevent leakage in the Be it known that I, JOS PH CLARENCE finished product.

BOLT, a citizen of the'United States, and a The process and apparatus are fully disresident of Boundbrook, county of Somerset, closedin the specification and drawing here- 5 State of New Jersey, have invented certain in, it being understood, however, that the new and useful Improvements in Methods showing is of one embodiment of the invenand Apparatus for Vul-canizing Inner Tubes tion only, and changes and modifications may or the like, of which the following is a specibe made within the scope of the invention fication. I Y and the claims forming a part hereof.

10 This invention relates to the vulcanization In the drawings: of inner tubes such as used in pneumatic Figure -1 is a view of a tube vulcanizing tires for vehicles, and is directed to certain mold of'any preferred type;

steps in the method of curing or vulcaniz- Figure 2 is an enlarged sectional view of ing such tubes, whereby certain advantages the mold, at the valve stem; and s 15 are obtained over prior practices The in- T Figure 3 is aperspective view of the air vention also relatesto the apparatus used in valve cured within the tube, the tube being the process. cut away to show the construction.

More specifically described, the invention The mold-is indicated by the numeral 1.

relates to the vulcanization of inner tubes As stated above, it may be of any preferred 2U by'molding, as distinguished from the usual type suitable for the vulcanization of an process of wrapping the tubes and curing nner tube. F or this. purpose it may be'made them upon poles or mandrels within fabric 1n two halves provided with any suitable casings or wrappers, or upon poles or manmeans 2 b which the halves may be secured drels without wrapping, By the molding together uring the curing of the tube. In

molds and by the process many advantages zation'ofthe rubber, the'walls of the mold are obtained. The tubes are molded within may be-chambered for the reception ofsteam, heated jackets or mold sections and are sub-v or the mold may be placed between hot jected t6 the internal pressure of any suitplates. Any other means may be. employed,

30 able fluid, such as steam or steam and air' in all of which will be understood by those combination orvarious inertgases and fluids. skilled in the art.

The present invention has for its direct The rubber tube, a portion-(of which is object the rovision of aprocess and appashown in the drawing is indic'fitedby the nuratus by w 'ich the valve stem is molded in meral 3 and the valve stem ,by; the numeral the inner tube, whereby an air tight connec- 4. The valve stem is of theufsiial construe tion is simply, cheaply and effectively obt-ion, being providedwit-h an enlarged base tained between the valve and the tube with 5 and a screw-threaded stem 6, the outer out the use of added reinforcements other end of the stem being reduced to form a nipthan the usual valve patch. Attempts have ple 7 to which, in the process of vulcaniza process the tubes are cured within circular order to hea'tthe tube to perform the vulcanii 4 been. made to mold the air valve directly tion, a source of pressure-may be attached r I within the tube, but, so far as known to me, for the introduction-of a fl'ui'dor fluids under no one has succeeded in accomplishing this pressure, it being understood that fluids may result efli'ectively, due largely to the fact that be used for the purpose of expanding the thepressure within the tube'duringvuloanitube into the cavity of the mold or used for F 4 'zation, at which time the rubber is soft, has curing the tube.

forced the valve through the wall ,of the On thevalve stem is mounted in service tube to such an extent that the tube will leak the ring washer 10 and the, nut 1l,the for-. about the valve stem either immediately'or mer being loosely received over the valve such leaks will develop with later use' of the stem and the latter being screwed upon the 5 tube. i threaded portion of the valve stem. On the 1 By the use of my process and apparatus, inner circumference of the mold sections are however, I am enabled to o ercome thisdiffiprovided extensions 12 which are provided culty and have,.in addition, utilized the preswith radial recesses in which the valve stem sure within the tube to secure a proper emis received. 55 bedding of the valve within the wallof the In the wall of thetube at the valve are usually embedded one or two layers of fab- .ric 13 which reenforce the tube about the .the base of the valve has been brought into f contact with the layers of fabric, which have subsequently afforded passageways for the escape of the pressure. Heretofore, another drawback has been that the'short channel usually provided for the valve stem in the mold has oftentimes resulted in the operative incorrectly positioning the. valve and the tube in the mold. Also in prior processes the weight of the ringwa-sher and the fact that it loosely fits on the valvevstem has oftentimes resulted in. its sagging-on the stem.

' Accordingly it frequently encounters the edge of the recess provided for it andis thus held out of its proper place resultin in mi's placement thereof in the finished tu e.

, By my process I propose to utilize both the pfessure within the tube and the softening of the rubber to obtain a more secure fastening of the Valve stem within the tube,

and also to insure an accurate positioning of the tube, the valve stem and the ring washer.

The correct positioning of the tube and the valve stem is obtained by the provision of the extension 12 which supports the valve stem during the curing operation. At the innor end of the channel between the two mold halves which receive the valve stem, there -'depth. as the thickness oftlfe ring washer.

\ ing jammed due to its tendency to tilt or get The wall of this recess is slightly tapered so that-the ring washer will readily seat and will be guided into position. This eliminates any danger of the loose ring washer becomout of position. h r

The nut'iis received within the second recess 16, immediately 'belowthe recess 15 the nut being run down upon the valve stem to a light but firm fit against ring washer 10 before the tube is placed within the mold. The recess 16 is slightly greater in depth than the thickness of the nut, the amount being'variable as found desirable. I have found that "a depth approximately of an inch greater than the thickness of the nut is sufficient to accomplish the results desired pressure. is permitted to obtain asecure seating of the although this amount is not obligatory and i may be. altered.

nut, the pressure within the tube will force the valve base into the soft rubber of the tube tothe extent permitted by the recess 16 and no further, so that a firm embedding of the valve in the rubber is obtained, but not sufficiently to cause leakage either immediately or later The depth of recess 16 as compared with the thickness of nut 11 must ,be such that valve base5 is prevented from coming in contact with fabric patch 13.- I

As a result of the process described and by the use of the apparatus superior results are obtained in the curing of tubes under Suflicient movement of the Valve valve but the movement is arrested before the valve base comes in contact with the fabi ric patches 13. 1

Having explained the invention in detail, it will be understood that the principles thereof may be secured in other ways and by the use of other apparatus within the scope of the invention as set forth in the claims. WVhile the process has been described for the curing of tubes it may be applicable to other and analogous purposes.

What is claimed is: 1. The process of vulcanizing rubber tubes under internal pressure with the valve stem in position, comprising the step of permitting the valve stem to move outwardly as a result of the internal pressure while the rubber'is softened during vulcanization, and arresting the movement of the valve stem after the base thereof has become embedded within the rubberi i In the process of vulcanizing rubber tubes' under internal pressure, the step of inserting the valve stem within .the tube, 210- curately positioning the valve stem, applying heat. and pressure within the tube to cure it and permitting the base of the valve stem to become partially embedded within the tube wall by the pressure within the tube.

- 3. An apparatus for curing inner tubes I tube. I

- J OSEPH C. BOLT, 

